This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
As automobile and engine technology advance, the control systems utilized have become increasingly complex. To achieve compliance with stricter emissions and fuel economy standards, for example, many engines include electronic control modules. Typically, electronic control modules comprise closed-loop control circuits that monitor operating conditions and adjust various operating parameters in response to the monitored conditions. For example, a control module may receive data from various sensors located throughout the system and, in response, adjust any number of operating parameters of the system under control. Such dynamic adjusting typically causes the controlled system, such as an engine, to operate in a more desirable manner.
Electronic control modules typically include a number of electronic components physically and electrically coupled to a substrate, such as a printed circuit board. Because of the generally sensitive nature of the electronic components, coupled with the fact that the components may be subject to harsh environments, control modules have traditionally been placed within protective housings. The housings generally are configured to prevent ingress of contaminants, particularly moisture.
Unfortunately, the electronic components of the modules generate heat during operation and, resultantly, may induce an increase in the pressure and temperature of the ambient air disposed within the protective housing. Heated and pressurized air, if not relieved from the housing, may negatively affect the performance of the control module and may even damage the electronic components as well as the printed circuit board. Thus, the desire to prevent ingress of contaminants, particularly moisture, may be incongruous with the desire to allow egress of the pressurized and heated internal air.
Accordingly, many electronic control modules have been equipped with vent assemblies that allow egress of pressurized and heated air while simultaneously preventing ingress of moisture. Typically, these vent assemblies comprise a waterproof, yet not air tight, membrane disposed within rubber grommet that extends through holes in the housing and printed circuit board. When installed, the rubber grommet creates a watertight mechanical seal by tightly engaging with portions of the printed circuit board and housing.
As a mechanical seal, however, the rubber grommet may be susceptible to loss of sealing engagement induced by vibrations or movements naturally found in operating environments, such as automobiles. In other words, repetitive movements within the automobile may cause the vent assembly to loosen from the housing, thereby weakening the sealing engagement and allowing ingress of contaminants, particularly moisture, between the housing and grommet assembly.
Furthermore, traditional rubber grommet vent assemblies may require dedication of a relatively large surface area on the circuit board. Generally, a printed circuit board is more cost effective if a larger portion of its surface area can be devoted to electronic circuitry rather than a mechanical sealing system. Moreover, because of the rubber or insulative composition of the grommet, it may electrically isolate the electronic components of the circuit board from circuit ground. For example, the components on top of the circuit board may require a path to circuit ground that extends to the opposite side of the board. A rubber grommet, however, may prevent such a path, and, as such, an additional via (e.g., hole) may be necessary. This additional via occupies valuable surface area leading to an increase in the cost of the module.
Additionally, installation of the rubber grommet assembly generally occurs after the various electronic components have been attached to the printed circuit board. Accordingly, good adherence to dimensioning on the circuit board may be necessary, leading to longer manufacture times and greater expenses. Moreover, installation of the grommet vent assembly may require a dedicated device solely employed for such installation. A dedicated device adds an additional expense with respect to manufacture and usurps already precious floor space at the manufacturing facility.